That time a master tech in Phoenix changed my mind about oil viscosity

I always ran 10w-30 in everything until I talked to a guy at a shop near Chandler who showed me his tear-down data on a 5w-20 engine that still looked new at 200k miles. Has anyone else seen real proof that lighter oil actually protects better in modern engines?

3 comments

3 Comments

the_rowan1d ago

Oil weight debates are like arguing about which flavor of air tastes better, but that Chandler guy sounds like he actually counted something more than just his paycheck. Maybe it's just me but I've seen enough engines run on the wrong stuff to know that modern clearances are tighter than my wallet after a vacation. 5w-20 in a 200k mile engine that still looks clean is pretty solid proof that the engineers aren't just making stuff up to sell more quarts. I'd still probably run 10w-30 in my old truck though, some things just need that thicker blanket.

dylan_ward1d ago

Honestly, I gotta push back on @the_rowan a little here. Those modern 5w-20 specs aren't about engineering genius, they're about CAFE standards and hitting fuel economy numbers on paper. Seen plenty of direct injection engines sludge up with that thin stuff because it doesn't hold up to heat soak like a proper 30 weight does. Ngl, a clean engine at 200k with 5w-20 just means the owner changed oil on time, not that the oil weight was some magic bullet.

fisher.jessica1d agoMost Upvoted

Buddy of mine ran 5w-20 in his old V6 Tacoma for years because that's what the manual said and he never read anything else. Engine crossed 280k before a deer took it out and when we pulled the valve cover to grab the alternator bracket, it looked almost new under there. No sludge, no varnish, just clean metal. Meanwhile I've got a neighbor who runs 20w-50 in his 90s Honda because "thicker is better" and that thing ticks like a sewing machine on caffeine. Hard to argue with what actually works.